Excavations have unearthed a fortified Canaanite city of the second millennium BCE. The Phoenician town of the first millennium BCE is known both from the Hebrew Bible and Assyrian sources. Phoenician Achzib went through ups and downs during the Persian and Hellenistic periods. In Roman times Acdippa was a road station. The Bordeaux Pilgrim mentions it in 333-334 CE still as a road station; Jewish sources of the Byzantine period call it Kheziv and Gesiv. There is no information about settlement at the site for the Early Muslim period. The Crusaders built a new village with a castle. During the Mamluk and Ottoman periods a modest village occupied the old tell (archaeological mound). This village was depopulated during the 1948 Arab-Israeli war. The only permanent resident of Achziv is an Israeli who has been welcoming visitors to a small stretch of beach where he has lived since 1975.

Achziv was the first fortified settlement found by archaeologists, is a large Canaanite port city from the Middle Bronze Age IIB (1800-1550 BCE).[1][2] The massive ramparts, some 4.5 m (15 ft) high, protected the city proper and a large area of port facilities. To the north and south the city extended to the two nearby rivers, which the Canaanite engineers connected by a fosse, thus transforming Achzib into an island.[1] A substantial destruction level from the beginning of the Late Bronze Age proves that even these fortifications were eventually not sufficient.[2]

During the reign of the Seleucids the border was established at Rosh HaNikra, just north to Achziv, making it a border city which they called Ekdippa (Έκδιππα in Ancient Greek) and put it under the control of Acre.

A maritime city named Cziv, nine miles (14 km) north of Acre, is mentioned by Josephus Flavius and later by Eusebius.
Achziv (Cheziv) is mentioned in Jewish rabbinic writings, for example Midrash Vayikra Rabba 37:4. Additionally, Achziv is mentioned in the Babylonian Talmud, and by the relating Middle Age commentators, concerning the location of Achziv in regards to historical borders of Israel.

During the Crusader period, the site was known as Casale Umberti,[5] or Casal Humberti, after Hubert of Pacy who held the casale and is documented in 1108.[6] European farmers settled there in 1153 under Baldwin III. In 1232 it was the site of the Battle of Casal Imbert between German and French Crusaders as part of the War of the Lombards.

^ abAvraham Negev and Shimon Gibson (2001). Achzib (b) A Canaanite city on the Mediterranean coast. Archaeological Encyclopedia of the Holy Land. New York and London: Continuum. p. 16. ISBN0-8264-1316-1.